The present disclosure relates to transfer-printing ink that is used when an image recorded on transfer paper by an ink-jet recording device is transferred to a recording sheet, and also relates to a method of transfer printing.
Conventionally, screen printing, roller printing, and the like are widely used as methods for printing on cloth such as cotton, silk, and polyester. These printing methods require different screen frames, engraved rollers, and the like for different print patterns, and are thus unsuitable for printing in small-volume large-variety production, They also require the washing-away of a sizing agent and the like, and produce large amounts of waste water, posing a problem of increased burden on the environment. In contrast, ink-jet printing does not require pattern-making for screen frames or engraved rollers, and allows change of print patterns and colors simply through change of digital data; it is thus suitable for small-volume large-variety production. Also, ink-jet printing produces far less waste water. It has thus come to be used increasingly widely today.
Known ink-jet printing methods include a direct printing method, in which an image is printed directly on cloth on an ink-jet printer, and a transfer printing method, in which an image is printed on special paper (transfer paper) on an ink-jet printer and then only the ink on the transfer paper is transferred to cloth on a thermal transfer device.
In a direct printing method, an image is printed while cloth is transported at high speed; thus, bringing an ink-jet head too close to the cloth causes, due to fluff on the surface of the cloth, wear and scratches on the ink-jet head. Thus, at least a given distance has to be left between the ink-jet head and the cloth. Inconveniently, a greater distance between the ink-jet head and the cloth tends to lead to a disturbed image, and cloth having an image printed inappropriately on it has to be scrapped.
On the other hand, a transfer printing method has, to name a few, the following advantages. The absence of a step involving direct transport of cloth to a printer makes a disturbed image less likely, and allows high-quality, high-definition printing of images on cloth. Owing to image printing using an ink-jet printer being performed on transfer paper, an inappropriately printed image does not require scrapping of cloth. Only a comparatively small distance has to be left between an ink-jet head and transfer paper, and this allows high-quality image printing with little contamination with ink mist.
One commonly practiced type of such transfer printing method is a sublimation printing method employing a sublimation dye. For example, one known type of sublimation ink-jet printing transfer paper has, on a base material, a sublimation printing ink reception layer containing a water-soluble resin and fine particles, and this design gives it superb ink absorption, drying speed, image reproduction, and resistance to striking-through.
Inconveniently, a sublimation printing method has, to name a few, the following disadvantages. It can be applied only to polyester fiber. Due to low molecular weights, some sublimation dyes have poor light-fastness, and their colors can migrate or fade during washing or under the heat of an iron. Due to high transfer temperatures, fiber can be compressed during transfer, leading to a degraded feel.
Against the background discussed above, there have been developed printing techniques that employ non-sublimation pigment ink and that can be applied to a wide range of fibers other than polyester fiber. For example, one known type of ink-jet printing ink is an ink composition containing a dispersion of a pigment with an average particle diameter of 200 μm or less and a maximum particle diameter of 500 μm or less, a water-soluble fixing agent, and a cross-linking agent, wherein a water-soluble pigment dispersing agent is obtained by neutralizing a particular emulsion polymer with a basic substance, the water-soluble fixing agent has a cross-linking functional group, and the cross-linking agent has a functional group that starts a cross-linking reaction with the cross-linking functional group of the water-soluble pigment dispersing agent and the cross-linking functional group of the water-soluble fixing agent at a temperature of 100° or higher.
For another example, one known type of ink-jet pigment printing ink is a pigment printing ink containing a pigment, water, and a water-soluble organic solvent, wherein the pigment is dispersed by a pigment dispersing agent, and the pigment dispersing agent is neutralized with a volatile amine and an inorganic base. For yet another example, a known transfer-printing method involves printing a pattern by ink-jet printing using a water-soluble dye on transfer paper coated with a hydrophilic sizing agent as an ink reception layer and then transferring the pattern to cloth containing a natural fiber as a main component.